An Electrospray Ion Source will be interfaced with an Ion Mobility Analyzer and performance characteristics studied under Phase I funding. To establish the potential for commercialization of this system detection sensitivity limits will be determined for a range of sample types. In addition, the upper mass range limitations of the Electrospray Ion Source will be explored and ion mobility spectra of large macroions will be studied. Optimization of the overall instrument hardware and operating parameters will be divided into four major tasks. The first will be to optimize the Electrospray region, second to redesign the present ESPI/IMA to accommodate the necessary changes, third to optimize the IMA performance using the redesigned hardware and fourth to study the upper mass limit of the ESPI source. With high enough sensitivity, the initial commercial application of the ESPI/IMA can be used as a detector system for Liquid Chromatography or Zone Capillary Electrophoresis. Used as a prefilter sample introduction ion source it can also be interfaced to Mass Spectrometer analyzer.